Stabilization of glyceride oils with oxydialkanoic acids



Patented July 14, 1953 a STABILIZATION OF GLYCERIDE OILS WITH OXYDIALKANOIC ACIDS Cyril D. Evans, John C. Cowan and Arthur W. Schwab, Peoria, 111., assignors to the United States of America as represented by the Secretary of Agriculture t No Drawing. Application October 5, 1951,

- Serial No. 250,009 Claims. (01. 2e0 39s.5),

(Granted under A non-exclusive, irrevocable, royalty-free license in the invention herein described, for all governmental purposes, throughout the world, with the power to grant sublicenses for such impurities.

Title 35, U. 8. Code (1952),

sec. 266) In the case of commercially refined edible oils of varied agronomic origin, the iron content has been found to vary as much as one hundred fold, ranging from 0.03 part per million Deodorization was carried out in a labpurposes, is hereby granted to the Government 5 upward. The copper content has been found to of the United States of America. vary as much as ten fold, from 0.01' part per mil- This invention relates to the treatment of lion up to 0.1 part per million. Moreover, the glyceride oils or fats and such related materials metal equipment with which the oil comes in as synthetically produced esters of long chain contact during handling is believed to contribute fatty acids and edible compositions comprising somewhat to the heavy metal content of the oil. fats of animal or vegetable origin. It relates As previously mentioned, the oxydialkanoic particularly to the treatment of such fatty subacids give excellent results in general to produce stances to prevent oxidative deterioration and an oil with improved oxidative and flavor stato increase the storage life of such fatty subbility, thus increasing the storage life of the stances, particularly as food materials. oil. 'Oxydiacetic acid is especially effective in Glyceride oils of animal or vegetable origin stabilizing oils which have abnormally high iron are known to deteriorate more or less rapidly in content. storage and to develop off-flavors and odors which According to our invention, the addition of the reduce their utility and value as food materials stabilizer is relatively simple, since it is readily or as ingredients in pharmaceutical or cosmetic Q dispersible in the oil, and the addition may be compositions. This deterioration is mainly due eflected at any desired stage in the conventional to oxidative processes which are extremely difiitreatment of the oil. For example, it maybe cult to control. Difiiculty of control is due largely added to the raw oil, or it may be added at any to the presence of small quantities of metals convenient stage of conventional refining. For which act as autoxidation catalysts. the sake of convenience in a process involving According to this invention, glyceride oils refining followed by deodorization, we prefer to which contain small quantities of metallic conadd the stabilizer to the oil before the steam destituents of the class which possesses oxidative odorization step. By our invention, we are thus catalyticproperties are treated to remove such able to produce a raw oil or a refined oil, or food, metals or to neutralize their catalyticefiect, thus pharmaceutical, or cosmetic compositions with increasing the 'oXidative stability of the oil. improved stability. Wehave discovered that oxydialkanoic acids, We add to the oil an amount of stabilizer particularly those in which the alkane chain beranging from 0.001 to 0.1 percent based on the tween the carboxyl group and ether linkage is weight of the oil. In the following examples, less than 3 carbon atoms in length, such as samples of vegetable oils were treated with the oxydiacetic acid (diglycolic acid) and oxydidesignated oxydialkanoic acid just before the depropionic acid, when added to the glyceride oils odorization step of a conventional refining proor fats, or the glyceride derivatives previously cedure. mentioned, impart improved flavor and oxidative oratory steam deodorizer for three hours at 210 Stability. These acids pp y hav the ab l- 40 C. Control samples containing no stabilizer ity to nullify the catalytic action of the metals, were also subjected to the tests for purposes of such as iron and copper, which commonly act comparison. As a further basis for comparison, as autoxidation catalysts in oils. oil samples containing added catalytically active Accordingly, we utilize our discoveries to inmetals were also evaluated, both with and withcrease the oxidative stability and the flavor sta- 5 out the stabilizer. biliby 0f y d particularly vegetable oils, A chemical evaluation, based on the active such as soybean oil, cottonseed oil, peanut oil, oxygen method (Swift stability test), was made, mustard seed oil, corn oil, perilla oil, safllower which provides the peroxide values, taken after oil, and the like, by adding thereto stabilizing the samples are blown with air for 8 hours at amounts of the oxydialkanoic acids. The ef- 208 F. These are termed the A. O. M. values. fect of this stabilizer is pronounced, particularly The oils were also evaluated organoleptically. in the case of oils bearing appreciable amounts The taste panel W s Composed of Persons Skilled of dissolved iron. in taste testing, and the flavor scores given be- Glyceride oils vary in their natural stability, low are based on a 1 to 10 scoring system in which and also vary in their content of heavy metal the highest score is 10. A flavor score of 6.0

or higher indicates an acceptable oil. The results are tabulated below.

4 4. The composition of claim 2 in which stabilizer is oxydipropionic acid.

the

TABLE Control 0.01% oxydiacetic acid 0.01% oxydipropionic acid 01 Flavor score Flavor score Flavor score A.O.M A.O.M A.O.M

M fitt d t 53th m it??? time 60 '0. 60 '0 60 '0.

Oil No. 1, soybean 30. 1 Oil N0. 2, soybean 15. 7 Oil No. 2+0.3 p. p. m. Fe. 64. 0 Oil No. 3, soybean 25. 6 Oil No. +0.1 p. p. m C 77.0 Oil No. 4, soybean 44. 0 Oil No 4+0.3 p p m 96. 7 Oil No 5, soybean" 47.1 Oil No 6, soybean 1 50. 5 Oil No. 7, cottonseed -l 37. 5

1 At concentrations of oxydiacetic acid of 0.1% and 0.001% the A. 0. respectively.

Likewise, we may substitute for the vegetable oils in the foregoing examples, others such as corn oil, perilla oil, safflower oil and the like, or hydrogenated vegetable oils, animal oils and fats, such as lard, lard oil or tallow. Moreover, corresponding stabilizing efiects are obtained in preventing the oxidative deterioration of the raw glycerides.

The stabilizing efiect of the oxydialkanoic acids of this invention has been explained in part in the foregoing specification by the ability of the stabilizers to nullify the deleterious effects of heavy metal autoxidation catalysts present in the oil. It is to be understood that this invention is not limited to such explanation, inasmuch as we have found that our stabilizers are effective in preserving the odor and taste of the oils without specific dependence on the presence of autoxidation catalysts.

We claim:

1. A new composition of matter, a glyceride oil and a stabilizing amount of one of the group consisting of oxydiacetic acid and oxydipropionic acid.

2. A new composition of matter as described in claim 1 in which the glyceride oil is of vegetable origin and the stabilizer is present within the range of 0.001 to 0.1 percent based on the weight of the oil. 7

3. The composition of claim 2 in which the stabilizer is oxydiacetic acid.

M. values for this oil were 4.1 and 41. 8,

8. Process of claim 7 in which the oxydialkanoic acid is oxydiacetic acid.

9. Frocess of claim 7 in which the oxydialkanoic acid is oxydipropionic acid.

10. In a process for refining a glyceride oil which includes the conventional steps of refining and steam deodorization, the improvement which comprises adding to the oil 0.001 to 0.1 percent oxydialkanoic acid prior to said deodorization.

CYRIL D. EVANS.

JOHN C. COWAN.

ARTHUR W. SCHWAB.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,369,640 Barnum Feb. 20, 1945 2,397,976 OLeary Apr. 9, 1946 

1. A NEW COMPOSITION OF MATTER, A GLYCERIDE OIL AND A STABILIZING AMOUNT OF ONE OF THE GROUP CONSISTING OF OXYDIACETIC ACID AND OXYDIPROPIONIC ACID. 